1. Field of the Invention
The present invention relates to a computer, and more particularly, to a portable computer, which can lower power consumption of a card bus controller.
2. Description of the Prior Art
Please refer to FIG. 1, which is a function block diagram of a prior art portable computer 10. The portable computer 10 comprises a processor 12 for controlling operation of the computer 10, two card bus slots 14 connected to the processor 12 for connecting to a PCMCIA card, a power supply 16 for providing the PCMCIA card inserted into the card bus slot 14 with electric power, and a card bus controller 18 connected to the processor 12 for controlling the power supply 16 and the PCMCIA cards inserted into the card bus slot 14. Furthermore, the processor 12 communicates with the card bus controller 18 via a peripheral component interconnect (PCI) bus 8.
The power supply 16 is capable of providing different voltages for different PCMCIA cards inserted into card bus slot 14 via ports 11, 13. The card bus controller 18 controls the power supply 16 through port 19 for providing the PCMCIA card with an optimum voltage according to the specification of the PCMCIA card inputted at ports 15, 17. However, the card bus controller 18 is always turned on no matter whether there is any PCMCIA card inserted into the card bus slot 14, and increases the power consumption of the computer 10.